Optical sensing systems, such as LiDAR systems, have been widely used in autonomous driving. LiDAR systems are used to detect the position, speed, and even contours of an object in the environment and also to produce high-definition maps. For example, a typical LiDAR system measures a distance to a target by illuminating the target with pulsed laser beams and receiving the reflected pulses with a sensor, such as a photodetector. Differences in the wavelengths and/or return time of the laser beams can then be used to calculate the distance and to make digital three-dimensional (3D) representations of the target. Because using a laser beam as the incident light can map physical features with high resolution, a LiDAR system is particularly suitable for applications such as sensing in autonomous driving and/or high-definition map surveys.
A LiDAR system normally includes a transmitter that emits pulsed laser beams. The transmitter further has one or more laser emitters. Within the same length or area of the transmitter, the more laser emitters are provided, the more laser beams the LiDAR system emits for scanning, and thus the higher resolution the LiDAR system achieves. As a result, the resolution of the LiDAR system typically depends on the density of the laser emitters provided along a direction or within an area of the transmitter.
Existing multi-beam LiDAR systems include multiple laser emitters. In order to achieve higher resolution of detection, the conventional wisdom is to mount as many laser emitters as possible. Therefore, the transmitter circuits of the system have grown highly complicated along with the increasing size thereof. Also, the existing arrangement of laser emitters on laser emitter boards renders the existing LiDAR systems difficult to obtain satisfying resolution in the middle part of its field of view, and consequently fails to acquire information from this region of interest (ROI) for subsequent data processing and point cloud reconstruction. Other problems which traditional LiDAR systems suffer from include sophisticated internal structure, high overall weight, and short life cycles.
Embodiments of the present disclosure address the above problems by providing LiDAR systems using multi-beam laser emitters with two types of laser emitter boards and also methods for detecting objects in the surrounding environment using the same.